1Field of the Invention
The present invention relates to probe electrodes for use in apparatuses for electroanalysis, current-potential measuring, electrolysis reaction and the like and a method of producing the same.
2Prior Art Statement
In the aforementioned apparatuses, a new electrode surface has to be used each time a different measurement or reaction is conducted to ensure an accurate electrode reaction.
Mercury drop-feed electrodes are well known as electrodes for such applications. In the mercury drop-feed electrode, an insulating slender pipe is filled with mercury and the mercury present at the tip of the slender pipe serves as an electrode. The mercury used as an electrode at the tip of the slender pipe is dropped each time a different measurement or reaction is conducted. This arrangement is extremely convenient because a hew electrode surface is readily obtainable. However, mercury is usable as an electrode on only the negative side since its elution potential is approximately +0.27 V. Because of its strong toxicity, moreover, the waste electrode thus dropped has to be recovered for treatment. For this reason, there has developed a demand for a new electrode as a substitute for mercury in consideration of the problem of environmental pollution, which is severely regulated law.
On the other hand, gold or platinum electrodes, or carbon electrodes of graphite or amorphous carbon prepared from sintered carbon material are employed on the positive potential side. Notwithstanding, the gold or platinum electrode is expensive and has to be electrochemically washed in a nitric acid solution to obtain a new electrode surface. In the case of the carbon electrode, it is necessary to carry out the troublesome process of mechanically polishing the surface to obtain a new electrode surface or of electrolytically oxidizing the surface at a very high positive potential. The carbon electrode has additional disadvantages in that it is not only vulnerable to mechanical shock but also insufficient in mechanical strength since it is a sintered material. A strong electrode in the form of a needle that can be thrust into an object being examined is consequently unavailable and, if a binding material like clay is mixed with the carbon material to increase the mechanical strength, the mixture may act as what arrests the electrode reaction. Such an electrode is therefore unusable for accurate reaction measurement.